SSH Tunneling

ssh-tunnel.sh

#!/bin/bash
#
# SSH Tunnel Manager
#
# SSH Flags:
# f - Force to background.
# N - Execute no commands. Don't open shell.
# q - Run quietly.
# T - Don't allocate pseudo TTY.
# R - Reverse Proxy.
# L - Local proxy.
#
# Usage: 
#   bash <(curl -skL http://bit.ly/ssh-tunnel) -server tunneluser@gateway.com
#

GATEWAY=""
BASEPORT=18000

usage() {
  cat << EOF
  $0

  Establishes SSH Tunnels from Client and Server to a Gateway

  Usage: $0 <-server|-client|-close> GATEWAY BASEPORT

  -server     Run server Mode
  -client     Run client Mode
  -close      Close open connections

  GATEWAY     Login on a server
  BASEPORT    Port to open tunnel on
              BASEPORT must be unique for each server hooking up to the gateway.

  PASSWORDS
  =========
  You will be asked to enter password to setup the SSH tunnel each time. To avoid typing in passwords,
  you might want to use SSH keys.

EOF
}

server() {
  echo BASEPORT is $BASEPORT
  echo "Setting up tunnel for SSH: $((BASEPORT))"
  nohup ssh -fNTR $((BASEPORT)):localhost:22 $GATEWAY
}

client() {
  echo BASEPORT is $BASEPORT
  echo "Setting up tunnel for SSH: $((BASEPORT))"
  nohup ssh -fNqL $((BASEPORT)):localhost:$((BASEPORT )) $GATEWAY
}

close() {
  case $OSTYPE in
    darwin*)
      FIELDNUM=3
      ;;
    *)
      FIELDNUM=2
      ;;
  esac
  echo $FIELDNUM
  ps -ef | grep ssh | grep $((BASEPORT)) && \
      ps -ef | grep ssh | grep $((BASEPORT)) | tr -s " " | cut -d " " -f ${FIELDNUM} | xargs -n 1 kill -9
}

if [ "$3" != "" ]; then
  BASEPORT=$3
fi
if [ "$2" != "" ]; then
  GATEWAY=$2
fi
if [ "$GATEWAY" = "" ]; then
  usage
  exit 1
fi
case $1 in
  -server)
    echo Running SSH Tunnel in Server Mode
    server
    ;;
  -client)
    echo Running SSH Tunnel in Client Mode
    client
    ;;
  -close)
    echo Closing open SSH Tunnels
    close
    ;;
  *)
    usage
esac